Linear Flux-Shuttle Current Source Without Bias Resistor Networks
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Solution Overview
Problem
Superconducting circuits using Josephson junctions face challenges with spurious magnetic fields and heat due to high power dissipation in bias resistor networks, which dominate the power budget and can lead to dithering effects in flux-shuttle loop current sources.
Innovation Solution
A linear flux-shuttle current source system is introduced, comprising Josephson transmission line stages with Josephson junctions, output inductors, and clock inputs, where an AC clock signal inductively couples bias current to trigger Josephson junctions in a sequence to generate a DC output current, eliminating the need for bias resistor networks and preventing dithering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a bias resistor network is used to provide DC bias current to Josephson junctions, then the DC bias current is supplied, but spurious magnetic fields and heat are generated due to high power dissipation
Solution Approach 1:
The patent extracts and removes the bias resistor network from the system by introducing a linear flux-shuttle current source that generates DC bias current through a superconducting flux-pumping mechanism, thereby eliminating the source of spurious magnetic fields and heat while maintaining the necessary DC bias current supply to Josephson junctions
Solution Approach 2:
The patent replaces the resistive (thermal) mechanism of bias current generation with a superconducting flux-pumping mechanism using Josephson transmission line stages, where AC clock signals inductively couple bias current through Josephson junctions in a sequence to generate DC output current without resistive power dissipation
2Use of energy by moving object
If a bias resistor network is used to provide DC bias current, then the current is supplied continuously, but the power budget is dominated by static power consumption regardless of device switching state
Solution Approach 1:
The patent employs periodic AC clock signals to drive the linear flux-shuttle stages, which pump flux sequentially through Josephson junctions to generate DC bias current only when needed, replacing continuous resistive power consumption with periodic superconducting flux-pumping action that eliminates static power dissipation
Solution Approach 2:
The linear flux-shuttle current source generates its own DC bias current output through the superconducting flux-pumping action driven by AC clock signals, eliminating the need for external bias resistor networks and enabling the system to supply its own bias current without continuous power dissipation
3Power
If a flux-shuttle loop current source is used, then DC current is generated, but dithering effects occur due to power dissipation issues
Solution Approach 1:
The patent extracts the problematic power dissipation element (bias resistor network) from the flux-shuttle system and replaces it with a linear array of superconducting JTL stages that generate DC current through flux-pumping without resistive losses, thereby eliminating the root cause of dithering effects and improving stability
Solution Approach 2:
The patent changes the fundamental operating parameters of the current source by transitioning from resistive bias current generation to superconducting flux-pumping, where AC clock signals induce sequential Josephson junction triggering to produce DC output current, fundamentally altering the power dissipation characteristics and eliminating dithering
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The linear flux-shuttle system reduces power dissipation, mitigates dithering, and allows for scalable and efficient DC current generation with improved circuit layout and performance, enhancing the reliability and efficiency of superconducting current sources.
Implementation Method 1
an AC clock signal inductively couples bias current to trigger Josephson junctions in a sequence
Implementation Method 2
Each of the JTL stages includes at least one Josephson junction... in response to the at least one Josephson junction triggering in a sequence
Data Source
AI summary
One example describes a superconducting current source system comprising a linear flux-shuttle. The linear flux-shuttle includes an input and a plurality of Josephson transmission line (JTL) stages. Each of the JTL stages includes at least one Josephson junction, an output inductor, and a clock input. The linear flux-shuttle can be configured to generate a direct current (DC) output current via the output inductor associated with each of the JTL stages in response to the at least one Josephson junction triggering in a sequence in each of the JTL stages along the linear flux-shuttle in response to receiving an input pulse at the input and in response to a clock signal provided to the clock input in each of the JTL stages.